Light emitting device

ABSTRACT

A light emitting device includes a package equipped on a front face with a window for installing a light emitting element, and outer lead electrodes that protrude from a bottom face of the package. The package has, on the bottom face, two side face convex components provided on the side face sides and a center convex component provided at a center. The outer lead electrodes are housed in a concave components defined by the side face convex components and the center convex component. The side face convex component has groove provided on the side face.

CROSS-REFERENCE TO RELATED APPLICATIONS

This national phase application claims priority to Japanese PatentApplication No. 2008-029267 filed on Feb. 8, 2008 and Japanese PatentApplication No. 2008-225506 filed on Sep. 3, 2008. The entiredisclosures of Japanese Patent Application Nos. 2008-029267 and2008-225506 are hereby incorporated herein by reference.

BACKGROUND INFORMATION

1. Technical Field

The present invention relates to a light emitting device, and moreparticularly to a light emitting device which is a surface-mounted typewith thin and small size

2. Related Art

Recent years have witnessed the development of high output semiconductorlight emitting elements, and light emitting devices in which these areused, and these have been used in a wide range of fields. Advantages tosuch light emitting devices are that they are compact, have low powerconsumption, are lightweight, and so forth, so they have been put to useas light sources for backlights of LCD (Liquid Crystal Display) inportable telephones and the like, as light sources for various gauges,as various kinds of reading sensors, and so on (for example,JP-2003-78172-A).

SUMMARY

It has been disclosed in JP-2003-78172-A that a lead, for supporting apackage up until the end of a process of bending outer lead electrodesof a light emitting device, is provided to part of a lead frame.

FIG. 12 shows the state midway through the manufacture of the lightemitting device discussed in JP-2003-78172-A. In FIG. 12, a package 7has leads 4 b and 4 c provided to the top face 10 of the package, leads4 a and 4 d provided to the side faces of the package 7, and leads 4 eprovided to the bottom face of the package. The ends of the leads 4 a to4 d are embedded in the package 7, thereby supporting the package 7.

The leads 4 e are cut and bent at the broken line portions in thedrawing, and are portions that serve as outer lead electrodes. Cuttingthe leads 4 e at the broken line portions results in a state in whichthe package 7 is supported by the leads 4 a to 4 d. The leads 4 e aresubjected to bending in this state. After this, the now-unnecessaryleads 4 a to 4 d are removed from the package to obtain a light emittingdevice.

However, depending on the conditions under which the package is formed,the package molding material may flow along the leads 4 a to 4 d andform flash when the leads 4 a to 4 d are removed. Consequently, theexternal size of the package 7 ends up being larger than the designeddimensions, albeit only partially. Particularly in the case of a thinlight emitting device, the thickness H1 of the package must be reduced,so such flash is undesirable on the top face. Flash that does occur canbe taken off by cutting in a subsequent step, for example, but this addsanother step and adversely affects production efficiency. Furthermore,since this flash is not always formed in the same size, its removal isdifficult to manage with a computer program or the like, so it is notsuited to mass production.

Accordingly, with a thin light emitting device, the leads that supportthe package (hereinafter referred to as support leads) are usuallydisposed where any flash that should occur will have little effect, thatis, only on the side faces of the package.

Also, to reduce the thickness of a light emitting device, outer leadelectrodes are extended from the side face-side of the bottom face ofthe package, and concave components are provided that can accommodatethe outer lead electrodes. This does minimize the increase in thicknessof the light emitting device attributable to the thickness of the leadframe, but there is a corresponding decrease in the thickness of theside faces of the package. In the manufacturing process, the supportleads must be wide enough for the package to the stably supported by thelead frame.

However, if the above-mentioned light emitting device is made smallerwith its shape left unchanged, the package side faces also becomethinner, so the support leads embedded therein become finer.Consequently, these leads are more prone to being twisted out of shape,and defects such as tilting of the package are more apt to occur. Also,the stress exerted on the package during bending of the outer leadelectrodes may cause the narrow support leads to be twisted and thepackage to be tilted. If the package tilts, the light emitting elementcannot be mounted, so this is a cause of defective products. Also, whena thin light emitting device is mounted on a substrate or the like, ifthere are differences in the height of the outer lead electrodes, ordifferences in the amount of solder applied to the mounting landpattern, then a mounting defect known as the Manhattan phenomenon mayoccur, in which a difference in surface tension when the solder melts,or shrinkage stress when the solder solidifies, or the like results inthe outer lead electrode on one side being fixed in a state of beinglifted up.

In view of this, it is an object of the present invention to achieve athinner and smaller product as needed in the past, and in particular toprovide a light emitting device with which (1) a package fixed to a leadframe can be stably supported in the manufacturing process and (2)mounting defects can be minimized in the mounting of the light emittingdevice to a substrate or the like.

To accomplish the above purpose, present invention is characterized inthat a light emitting device comprises; a package equipped on a frontface with a window for installing a light emitting element, and outerlead electrodes that protrude from a bottom face of the package, thepackage having, on the bottom face, two side face convex componentsprovided on the side face sides and a center convex component providedat a center, the outer lead electrodes being housed in a concavecomponents defined by the side face convex components and the centerconvex component, the side face convex component having groove providedon the side face.

With the light emitting device, it is preferable that the package has atleast two cut-outs, and the outer lead electrodes are disposed directlyunder the two cut-outs, respectively.

With the light emitting device, it is preferable that the thickness ofthe side face convex components and the center convex component issubstantially the same as the thickness of the outer lead electrodes.

With the light emitting device, it is preferable that the thickness ofthe package is no more than 1.5 mm.

According to the light emitting device of the present invention, athinner and smaller light emitting device with which a package can bestably supported in the manufacturing process can be provided. Also,with the light emitting device of the present invention, mountingdefects can be minimized in the mounting of the light emitting device toa substrate or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an oblique view of the light emitting device according to thepresent invention;

FIG. 1B is a front view of the light emitting device shown in FIG. 1A;

FIG. 1C is a bottom plan view of the light emitting device shown in FIG.1A;

FIG. 1D is a partial enlargement view of the light emitting device shownin FIG. 1A;

FIG. 2A is an oblique view of an embodiment of the light emitting deviceaccording to the present invention;

FIG. 2B is a back view of the light emitting device shown in FIG. 2A;

FIG. 2C is a top plan view of the light emitting device shown in FIG.2A;

FIG. 2D is a right side view of the light emitting device shown in FIG.2A;

FIG. 2E is a left side view of the light emitting device shown in FIG.2A;

FIG. 2F is a bottom plan view of the light emitting device shown in FIG.2A;

FIG. 2G is an oblique view, which is viewed from obliquely upward, ofthe light emitting device shown in FIG. 2A;

FIG. 2H is an oblique view, which is viewed from obliquely downward, ofthe light emitting device shown in FIG. 2A;

FIG. 2I is a front view in the state that a molding member is not pottedof the light emitting device shown in FIG. 2A;

FIG. 3A is an oblique view of an embodiment of the light emittingdevices respectively according to the present invention;

FIG. 3B is a back view of the light emitting device shown in FIG. 3A;

FIG. 3C is a top plan view of the light emitting device shown in FIG.3A;

FIG. 3D is a right side view of the light emitting device shown in FIG.3A;

FIG. 3E is a left side view of the light emitting device shown in FIG.3A;

FIG. 3F is a bottom plan view of the light emitting device shown in FIG.3A;

FIG. 3G is an oblique view, which is viewed from obliquely upward, ofthe light emitting device shown in FIG. 3A;

FIG. 3H is an oblique view, which is viewed from obliquely downward, ofthe light emitting device shown in FIG. 3A;

FIG. 3I is a front view in the state that a molding member is not pottedof the light emitting device shown in FIG. 3A;

FIG. 4A is an oblique view of an embodiment of the light emittingdevices respectively according to the present invention;

FIG. 4B is a back view of the light emitting device shown in FIG. 4A;

FIG. 4C is a top plan view of the light emitting device shown in FIG.4A;

FIG. 4D is a right side view of the light emitting device shown in FIG.4A;

FIG. 4E is a left side view of the light emitting device shown in FIG.4A;

FIG. 4F is a bottom plan view of the light emitting device shown in FIG.4A;

FIG. 4G is an oblique view, which is viewed from obliquely upward, ofthe light emitting device shown in FIG. 4A;

FIG. 4H is an oblique view, which is viewed from obliquely downward, ofthe light emitting device shown in FIG. 4A;

FIG. 4I is a front view in the state that a molding member is not pottedof the light emitting device shown in FIG. 4A;

FIG. 5A is an oblique view of an embodiment of the light emittingdevices respectively according to the present invention;

FIG. 5B is a back view of the light emitting device shown in FIG. 5A;

FIG. 5C is a top plan view of the light emitting device shown in FIG.5A;

FIG. 5D is a right side view of the light emitting device shown in FIG.5A;

FIG. 5E is a left side view of the light emitting device shown in FIG.5A;

FIG. 5F is a bottom plan view of the light emitting device shown in FIG.5A;

FIG. 5G is an oblique view, which is viewed from obliquely upward, ofthe light emitting device shown in FIG. 5A;

FIG. 5H is an oblique view, which is viewed from obliquely downward, ofthe light emitting device shown in FIG. 5A;

FIG. 5I is a front view in the state that a molding member is not pottedof the light emitting device shown in FIG. 5A;

FIG. 6A is an oblique view of an embodiment of the light emittingdevices respectively according to the present invention;

FIG. 6B is a back view of the light emitting device shown in FIG. 6A;

FIG. 6C is a top plan view of the light emitting device shown in FIG.6A;

FIG. 6D is a right side view of the light emitting device shown in FIG.6A;

FIG. 6E is a left side view of the light emitting device shown in FIG.6A;

FIG. 6F is a bottom plan view of the light emitting device shown in FIG.6A;

FIG. 6G is an oblique view, which is viewed from obliquely upward, ofthe light emitting device shown in FIG. 6A;

FIG. 6H is an oblique view, which is viewed from obliquely downward, ofthe light emitting device shown in FIG. 6A;

FIG. 6I is a front view in the state that a molding member is not pottedof the light emitting device shown in FIG. 6A;

FIG. 7A is an oblique view of an embodiment of the light emittingdevices respectively according to the present invention;

FIG. 7B is a back view of the light emitting device shown in FIG. 7A;

FIG. 7C is a top plan view of the light emitting device shown in FIG.7A;

FIG. 7D is a right side view of the light emitting device shown in FIG.7A;

FIG. 7E is a left side view of the light emitting device shown in FIG.7A;

FIG. 7F is a bottom plan view of the light emitting device shown in FIG.7A;

FIG. 7G is an oblique view, which is viewed from obliquely upward, ofthe light emitting device shown in FIG. 7A;

FIG. 7H is a front view in the state that a molding member is not pottedof the light emitting device shown in FIG. 7A;

FIG. 8A is an oblique view of an embodiment of the light emittingdevices respectively according to the present invention;

FIG. 8B is a back view of the light emitting device shown in FIG. 8A;

FIG. 8C is a top plan view of the light emitting device shown in FIG.8A;

FIG. 8D is a right side view of the light emitting device shown in FIG.8A;

FIG. 8E is a left side view of the light emitting device shown in FIG.8A;

FIG. 8F is a bottom plan view of the light emitting device shown in FIG.8A;

FIG. 8G is an oblique view, which is viewed from obliquely upward, ofthe light emitting device shown in FIG. 8A;

FIG. 8H is an oblique view, which is viewed from obliquely downward, ofthe light emitting device shown in FIG. 8A;

FIG. 8I is a front view in the state that a molding member is not pottedof the light emitting device shown in FIG. 8A;

FIG. 9A is a schematic cross-sectional view showing the method forproducing the light emitting device according to the present invention;

FIG. 9B is a schematic cross-sectional view showing the method forproducing the light emitting device according to the present invention;

FIG. 9C is a schematic cross-sectional view showing the method forproducing the light emitting device according to the present invention;

FIG. 9D is a schematic cross-sectional view showing the method forproducing the light emitting device according to the present invention;

FIG. 10 is a schematic top plan view of a lead flame having the packageaccording to the present invention; and

FIG. 11 is a schematic top plan view of a lead flame having the packageaccording to the present invention; and

FIG. 12 is a view showing a conventional light emitting device duringthe production process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The best mode for carrying out the invention will now be describedthrough reference to the drawings. The modes discussed below, however,are just examples, and the light emitting device of the presentinvention is not limited to the following light emitting devices.Furthermore, names and numbers that are the same in the followingdescription refer to members that are the same or analogous, anddetailed descriptions thereof will not be repeated.

As shown in FIGS. 1A to 1I, a light emitting device 100 of the presentinvention has a package 102 equipped on its front face with a window 101for installing a light emitting element, and outer lead electrodes 116that protrude from the bottom face of the package 102. With the presentinvention, the package 102 has on its bottom face two side face convexcomponents 103 and a center convex component 104. The outer leadelectrodes 116 are bent and housed in the concave components 107 formedby the side face convex components 103 and the center convex component104. Grooves 106 are provided on the side faces of the side face convexcomponents 103.

Grooves 106

The grooves 106 are portions where the support leads are embedded upuntil the completion of the bending of the outer lead electrodes 116 inthe light emitting device manufacturing process. As shown in FIG. 10,support leads 113 are embedded in the side faces of the side face convexcomponents 103 and the side faces of the package 102. When the supportleads 113 are removed from the package 102 in a subsequent step, theportions where the support leads 113 were embedded become grooves. Theseportions that become grooves lie in substantially the same plane as aninner lead electrode 834 disposed inside the package 102, and the widthW2 of the grooves (shown in FIG. 1D) is substantially the same as thethickness of the inner lead electrode 834.

Side Face Convex Components 103

As shown in FIG. 1A, the side face convex components 103 are provided onthe side face 126 side of the bottom face of the package. The result ofthis configuration is that there can be grooves 106 not only on the sidefaces 126 of the package, but also on the side faces of the side faceconvex components 103, and as shown in FIG. 10, the width W1 of thesupport leads 113 does not have to be reduced with this layout.

Furthermore, when the light emitting device 100 is mounted on asubstrate or the like, the side face convex components 103 minimizemounting defects. The weight of the light emitting device increases andgravity comes into play as a result of the side face convex component103 being provided to the side face on the lifted up side prior to theouter lead electrode 116 on one side being soldered in place in a liftedup state. Consequently, lifting up of the outer lead electrodes issuppressed. This allows mounting defects to be minimized.

As shown in FIG. 8H, the lifting up of the outer lead electrodes can befurther suppressed if side face convex components 803 are providedcontiguously from the end on the front face side to the end on the backface side. Also, as shown in FIG. 8H, if convex components are providedso as to cover the outer lead electrodes as viewed from the side faceside, then even if some kind of force should be exerted from the sideface side of the light emitting device, problems such as the outer leadelectrodes being pushed and bent can be avoided. The convex componentsthat protect the outer lead electrodes may be provided integrally withthe side face convex components 103 (see the side face convex components803 in FIG. 8H), or may be provided separately. In this case, at leastone of them functions as a side face convex component, and the otherconvex component serves to protect the outer lead electrodes.

As shown in FIG. 1D, the width W3 of the side faces of the side faceconvex components 103 is preferably greater than the thickness of thelead electrodes, the effect of which is that the light emitting devicecan be installed stably when mounted on a substrate or the like. Also,the width W4 of the side face convex components 103 as seen from thefront face of the package is preferably greater than the depth W5 of thegrooves 106. This is because the grooves 106 are the portions where thesupport leads are embedded, so the package can be securely supported bythe lead frame. If the width W4 of the side face convex components 103is greater than the depth W5 of the grooves, then the side faces of theside face convex components need not be in the same plane as the sidefaces 126 of the package. Specifically, the side faces of the side faceconvex components 103 may be formed so that they stick out from the sidefaces 126 of the package 102, or so that they are recessed.

The side face convex components 103 in FIG. 1B have a trapezoidal shapein plan view, but may instead have some other shape, so long as thegrooves 106 can still be formed. Also, with the present invention, theside face convex components 103 each preferably have approximately thesame thickness H2. The phrase “have approximately the same thickness”here means that the thickness is substantially the same, and a heightdifference of from 0 to 0.05 mm is permitted. A configuration such asthis allows the light emitting device to be installed stably on amounting substrate or the like.

Center Convex Component 104

The center convex component 104 is formed in the center of the lightemitting device 100 as seen in a front view. The window 101 is formed inthe center convex component 104. As shown in FIG. 1A, the bottom face ofthe center convex component 104 may be formed flat, or it may have anuneven structure. The side face convex components 103 and the centerconvex component 104 refer to portions that stick out from a referenceface, using the bottom face of the package where the outer leadelectrodes 116 protrude as this reference face. The side face convexcomponents and the center convex component are indicated by the shadedregions in FIGS. 1B and 1C.

As shown in FIG. 1B, it is preferable if the thickness H2 of the sideface convex components 103 and the center convex component 104 issubstantially the same as the thickness of the outer lead electrodes 116in order to improve electrical connection between the mounting substrateand the light emitting device.

The phrase “the thickness is substantially the same” means that there issubstantially to height difference between part of the surface of theouter lead electrodes and the side face convex components 103 and thecenter convex component 104 on the bottom face of the package.Nevertheless, a height difference of 0 to 0.05 mm is permitted.

Concave Components 107

The concave components 107 are formed by being sandwiched between theside face convex components 103 and the center convex component 104. Theconcave components 107 house the outer lead electrodes 116 that are bentalong the bottom face of the package. This allows the outer leadelectrodes to be disposed on the package bottom face while reducing theoverall thickness of the light emitting device.

Cut-outs 230

As shown in FIG. 2C, two cut-outs 230 are formed in the package, and thebent outer lead electrodes 116 are preferably disposed directly underthese two cut-outs 230. In other words, the outer lead electrodes 116are exposed by the cut-outs 230 as viewed from the top face. This makesit possible to check where the outer lead electrodes are disposed. Also,since the outer lead electrodes 116 can be checked from the top face, itis possible to check the mounting state on the substrate when the lightemitting device is mounted on a mounting substrate.

Further, a cut-out may be formed in the back face of the package inaddition to the cut-outs 230. This cut-out can be formed, for example,at the place where the package molding material is poured in(hereinafter referred to as a gate). This keeps the gate from stickingout beyond the outermost part of the back face of the package.

Package 102

The package 102 of the present invention has the above-mentioned sideface convex components 103, the center convex component 104, and thegrooves 106. The front face of the package 102 is further equipped withthe window 101 for installing the light emitting element, serves as asupport that fixes and supports the outer lead electrodes 116, etc.,protruding from the bottom face of the package 102, and also has thefunction of protecting the light emitting element from the externalenvironment.

There are no particular restrictions on the package molding materialused in the present invention, but a liquid crystal polymer, apolyphthalamide resin, a polybutylene terephthalate (PBT), or any otherknown thermoplastic resin can be used. Known thermosetting resins canalso be used. In particular, if a semicrystalline polymer resincontaining high-melting point crystals, such as a polyphthalamide resin,is used, the resulting package will have high surface energy and goodadhesion to the sealing member (discussed below) that fills the insideof the window of the package. This prevents separation at the interfacebetween the package and the sealing member in the cooling step in thecourse of adding and curing the sealing member.

To reflect light efficiently from the light emitting element, a whitepigment such as titanium oxide may be mixed into the package moldingmaterial, or the package may be left translucent without mixing in awhite pigment, so that the resulting light emitting device has broadlight distribution.

Also, as shown in FIG. 10, the window 101 for installing the lightemitting element 118 is formed on the front face of the package 102.There are no particular restrictions on the shape of this window, and aslong as the light emitting element 118 can be installed and part of thesurface of the electrically connected inner lead electrode 834 isexposed inside the window and preferably on the bottom face of thewindow, the shape of the window may be circular, elliptical, triangular,quadrangular, a shape similar to these, etc. The inner walls of thewindow are preferably inclined. This allows light from the lightemitting element to be reflected by the inner walls of the window, andbe taken out in the front face direction more efficiently. Also, thedepth of the window 101 can be suitably adjusted according to the numberof light emitting elements to be installed, the bonding method, and soforth. The size of the window 101 is preferably larger, so as to obtaina broader light distribution. The bottom face and/or inner walls of thewindow 101 are preferably embossed, subjected to plasma treatment, etc.,to increase the contact surface area and improve adhesion with thesealing member discussed below.

Also, the front face may be formed in a single plane as shown in FIG.4A, or it may have stepped portions as shown in FIG. 1A.

As shown in FIG. 3I, projections 332 can also be provided to the bottomface of the window. Providing these projections 332 keeps a bondingmember (not shown) from leaking out to the wire bonding area when alight emitting element 318 is bonded via this bonding member.

As shown in FIG. 1B, the thickness H3 of the package refers to thedistance from the upper face of the package to the bottom face of theside face convex components 103 of the package, and in the presentinvention thinner is better for the purpose of achieving a thinnerproduct. The thickness H3 in the present invention is preferably no morethan 1.5 mm.

Also, as shown in FIG. 2H, the top and bottom faces of a package 202 canbe formed so that the thickness decreases from the front face sidetoward the back face side. A gate 234 that leads to the back face of thepackage can also be formed on the bottom face of the package 202. Withthis constitution, the gate diameter can be increased, and a lightemitting device 200 that is compact, has less flash, and is suited tomass production can be obtained.

Lead Electrodes

As shown in FIG. 10, the lead electrodes consist of the inner leadelectrode 834 disposed inside the package 102, and portions that becomethe outer lead electrodes 116 when cut off from a lead frame 117 at alater.

There are no particular restrictions on the material of the leadelectrodes as long as it is electroconductive, but it needs to haveelectrical conductivity and adhesion with the conductive wires and soforth that are the members electrically connected with the lightemitting element. A specific electrical resistance is 300 μΩ•cm or less.Favorable examples of materials that satisfy these requirements areiron, copper, iron-containing copper, tin-containing copper, andaluminum, iron, copper, or the like that has been plated with copper,gold, silver, or palladium. The gloss of the plated surface ispreferably between 0.2 and 2.0 from the standpoints of light take-offefficiency and manufacturing cost. The plating thickness is preferably0.5 to 10 μm.

Outer Lead Electrodes 116

The outer lead electrodes 116 are provided to supply electricity fromthe outside to the light emitting element 118 installed in the window101. With the present invention, the outer lead electrodes 116 stick outfrom the bottom face of the package 102, and are bent along the bottomface of the package and housed in the concave components 107.

Also, with the present invention, the outer lead electrodes 116 can besuch that their distal ends branch in two parts. For example, as shownin FIG. 1C, the mode can be such that the two distal ends extend inopposite directions from each other, with one distal end extendingtoward the side face 126 of the package. With a mode such as this, thesurface area of the outer lead electrodes 116 can be enlarged, and outerlead electrodes with good heat diffusion can be obtained even with athinner package.

As shown in FIG. 6H, the mode can also be such that outer leadelectrodes 616 have distal ends that branch in three parts.

As shown in FIG. 5F, the width W6 and the width W7 of the outer leadelectrodes can be varied as appropriate, such as having them besubstantially the same.

With the present invention, the outer lead electrodes are preferablydisposed so that they stick out beyond the widest portion of thepackage. If the outer lead electrodes are disposed so that they do notstick out beyond the side faces 326 on the back face side of thepackage, this prevents external force from being exerted on the outerlead electrodes during the mounting of the light emitting device orduring the shipping of the light emitting device, so deformation of theouter lead electrodes can be prevented. If the outer lead electrodes 316are disposed so that they do not stick out beyond the side faces on theback face side of the package, it is preferable to provide cut-outs 330(see FIG. 3C) in the back face of the package as discussed above. Thismakes it possible to check where the outer lead electrodes 316 aredisposed, and also allows connections during mounting to be checked fromthe top face.

Inner Lead Electrodes 834

Inner lead electrodes 834 are disposed on the inside of the package 102,and are provided in order to supply the light emitting element withelectricity obtained from the outside by the outer lead electrodes 116.

Light Emitting Element 118

The light emitting element 118 installed in the window 101 may be anyelement so long as it is called the light emitting diode and is formedfrom any semiconductor material. Examples of the element include onethat have the laminated structure containing an active layer and may beformed from various semiconductor such as nitride semiconductor, InN,AlN, GaN InGaN, AlGaN, InGaAlN and the like; group III-V compoundsemiconductor, and group I-VI compound semiconductor on a substrate.

With the light emitting device of the present invention, the lightemitting element 118 may consist of just one element or a plurality ofelements. In the latter case, a plurality of light emitting elementsthat emit the same color of light may be combined in order to improveluminosity. Also, color reproducibility can be improved by combining aplurality of light emitting elements that emit different colors of lightin order to accommodate RGB.

As shown in FIG. 10, these light emitting elements are fixed by abonding member (not shown) to the surface of the inner lead electrodes834 or the bottom face of the window 101 of the package 102. The bondingmember can be an epoxy resin, a silicone resin, or the like in the caseof a light emitting element formed by growing a nitride semiconductor onan insulating substrate (such as a sapphire substrate). Also, whendegradation by light or heat from the light emitting element is takeninto account, the rear face of the light emitting element may be platedwith aluminum, and a conductive paste, a low-melting point metal orother such brazing material, an Au—Sn eutectic material or other suchsolder, or the like may be used. With a light emitting element in whichelectrodes are formed on both sides, such as with a light emittingelement comprising a conductive substrate (such as GaAs) and emittingred light, the element is fixed by silver, gold, palladium, or anothersuch conductive paste.

Conductive Wire 112

As shown in FIG. 10, conductive wires 112 electrically connect the innerlead electrode 834 with the positive and negative electrodes of thelight emitting element 118.

The conductive wires 112 need to have good thermal conductivity,electrical conductivity, mechanical connectability, and ohmic propertieswith the electrodes of the light emitting element. A thermalconductivity is preferably at least 0.01 cal/(s)(cm²)(° C/cm), and morepreferably at least 0.5 cal/(s)(cm²)(° C/cm). When ease of work and soforth are considered, the diameter of the conductive wires is preferably10 μm or more, and 45 μm or less, and more preferably 25 μm or more,from the standpoints of ease of handling and ensuring adequate lightemitting surface area for the light emitting element, no more than 35 μmis still more preferable. Specific examples of such conductive wiresinclude those made of gold, copper, platinum, aluminum, and other suchmetals, and alloys thereof.

Sealing Member

With the present invention, the window 101 may be sealed by a sealingmember. This sealing member protects the light emitting element 118 andthe conductive wires 112 from the external environment. The lightemitting element 118 and the conductive wires 112 are covered by thesealing member by curing the material of the sealing member that hasfilled the inside of the window 101 of the package so as to cover thelight emitting element 118 and the conductive wires 112.

There are no particular restrictions on the material of the sealingmember, but examples include silicone resins, epoxy resins, urea resins,fluororesins, hybrid resins containing one or more of these, and othersuch translucent resins with excellent weather resistance. The sealingmember is not limited to being an organic material, and can also beglass, silica gel, or another such inorganic material with excellentlight resistance. Also, thickeners, light diffusers, pigments,fluorescent substances, and the like can be added to the sealing memberof the present invention as dictated by the application. Examples oflight diffusers include barium titanate, titanium oxide, aluminum oxide,silicon dioxide, calcium carbonate, and mixtures containing one or moreof these. The sealing member can also be given a lens effect by puttingits light emission face into the desired shape. More specifically, thisface can have a convex or concave lens shape, or it can have anelliptical shape as seen from the emitted light observation face, or aplurality of these shapes may be combined.

Fluorescent Substances

The sealing member used in the light emitting device of the presentinvention can also contain a fluorescent substance that changes thewavelength of the light from the light emitting element. An example ofsuch a fluorescent substance is a fluorescent substance that containsone of the following rare earth elements.

More specifically, examples include garnet type fluorescent materialshaving at least one element selected from a group consisting of Y, Lu,Sc, La, Gd, Tb and Sm, and at least one element selected from a groupconsisting of Al, Ga, and In. In particular, an aluminum-garnet-basedfluorescent material contains Al and at least one element selected froma group consisting of Y, Lu, Sc, La, Gd, Tb, Eu, Ga, In and Sm, and isactivated by at least one element selected from among the rare earthelements, and is a fluorescent material that emits light when excited byUV rays or visible light emitted from the light emitting element. Anexample is a yttrium-aluminum oxide-based fluorescent material (YAGfluorescent material), as well as Tb_(2.95)Ce_(0.05)A1 ₅O₁₂,Y_(2.90)Ce_(0.05)Tb_(0.05)Al₅O₁₂, Y_(2.94)Ce_(0.05)Pr_(0.01)Al₅O₁₂,Y_(2.90)Ce_(0.05)Pr_(0.05)Al₅O₁₂. Of these, the use of two or more kindsof yttrium-aluminum oxide-based fluorescent material with differentcompositions, containing yttrium, and activated by cerium orpraseodymium is particularly favorable for the purposes of the presentinvention.

A nitride-based fluorescent material is one that contains nitrogen, alsocontains at least one element selected from a group consisting of Be,Mg, Ca, Sr, Ba and Zn, and at least one element selected from a groupconsisting of C, Si, Ge, Sn, Ti, Zr and Hf, and is activated by at leastone element selected from among the rare earth elements. Examples of thenitride-based fluorescent include (Sr_(0.97)Eu_(0.03))₂Si₅N₈,(Ca_(0.985)Eu_(0.015))²Si₅N₈, (Sr_(0.679)Ca_(0.291)EU_(0.03))₂Si₅N₈ andthe like.

The method for manufacturing the light emitting device 100 of thepresent invention will now be described by dividing it into twoparts: 1. a method for manufacturing the package 102; and 2. a step ofmanufacturing the light emitting device 100 from the package 102.

1. Method for Manufacturing Package 102

A method for manufacturing the light emitting device of the presentinvention will now be described through reference to FIGS. 9A to 9D.

First, a piece of sheet metal is punched out, and the surface thereof ismetal plated, which forms a lead frame (not shown) having inner leadelectrodes, support leads and a portion that later becomes the outerlead electrodes.

Then, as shown in FIG. 9A, the inner lead electrodes 834, the supportleads 856, and the portion that later becomes the outer lead electrodesare placed between metal molds 846 and 848 for molding a package andwhich are split into upper and lower parts. The support leads 856 andthe inner lead electrodes 834 that are placed inside the package hereare positioned so as to be disposed in a cavity 862 between the molds846 and 848 that have the shape of the package 102, and are sandwichedbetween the molds 846 and 848. The ends of the support leads 856 remainembedded in the side faces of the package 102 until the package isremoved.

The upper mold 846 has a protrusion 866 for forming a window in thepackage, and concave components (not shown) corresponding to the centerconvex component 104 and the side face convex components 103 formed onthe bottom face of the package in a subsequent step. The lower mold 848is provided with a material pouring gate 864 and concave components (notshown) corresponding to the center convex component 104 and the sideface convex components 103 formed on the bottom face of the package in asubsequent step.

Then, as shown in FIG. 9B, a molding material 868 is poured into thecavity 862 between the molds 846 and 848 from the material pouring gate864 of the lower mold 848.

Next, as shown in FIG. 9C, the molding material 868 is cured, and asshown in FIG. 9D, first the lower mold 848 is removed, and then theupper mold 846 is removed.

The above series of steps gives the lead frame 117 with the attachedpackage 102 as shown in FIG. 10. Specifically, the molded package 102has the side face convex components 103 on its bottom face, and isequipped with the inner lead electrode 834 exposed on the inside of thewindow 101. The inner lead electrode 834 is linked to the portion thatbecomes the outer lead electrodes 116 at a later by cutting from thelead frame. The support leads 113 are embedded in the side faces of thepackage 102 and in the side faces of the side face convex components103. In this state, the package 102 is supported on the lead frame 117by the support leads 113 and the portion that sticks out from the bottomface of the package, and later becomes the outer lead electrodes 116.

In FIG. 10, just one package 102 was used in the description, but asshown in FIG. 11, usually there are numerous packages 102, 102 . . . (inthis drawing, three vertically and two horizontally, for a total of six)formed on a single lead frame 117. When numerous packages 102, 102....are to be manufactured, molds 846 and 848 having numerous packagecavities 862 are used, and molding material is poured in simultaneouslythrough these cavities 862, which allows all the packages 102, 102 . . .to be formed at the same time.

2.Method for Manufacturing Light Emitting Device 100

A method for manufacturing the light emitting device 100 using thepackage 102 obtained in the above manufacturing method will now bedescribed through reference to FIGS. 10 and 11.

After the light emitting element 118 is placed in the window 101 of thepackage 102, the positive and negative electrodes of the light emittingelement 118, and the inner lead electrode 834 disposed inside thepackage are electrically connected to each other by the conductive wires112.

Next, the window 101 of the package 102 is filled with a sealing memberto seal the light emitting element 118 and the conductive wires 112.

The lead frame 117 is then cut away at the positions marked by thedotted lines X in FIG. 10, resulting in a state in which the package 102is supported by the support leads 113.

Next, the portions that have become the outer lead electrodes 116 afterthis cutting are bent along the bottom face of the package 102. At thispoint the outer lead electrodes 116 may be further bent along the sidefaces 126.

Also, as shown in FIG. 11, if a plurality of packages 102 is formed on asingle lead frame 117, then the bending of the outer lead electrodes canbe performed simultaneously for the plurality of packages 102, whichimproves the manufacturing efficiency of the light emitting device.

Finally, the package 102 is removed from the support leads 113 to obtainthe light emitting device 100 shown in FIG. 1.

EXAMPLE 1

Examples of the light emitting device of the present invention will nowbe described in detail, but the present invention is not limited to justthe examples given below.

As shown in FIGS. 1A to 1D, the light emitting device 100 of the presentinvention has a package 102 equipped on its front face with a window 101for installing a light emitting element, and outer lead electrodes 116that protrude from the bottom face of the package 102. With the presentinvention, the package 102 has on its bottom face two side face convexcomponents 103 and a center convex component 104. The outer leadelectrodes 116 are housed in the concave components 107 formed by theside face convex components 103 and the center convex component 104.Grooves 106 are provided on the side faces of the side face convexcomponents 103.

In this example, first a lead frame is formed in which the surface of apiece of sheet metal composed of iron-containing copper with a thicknessof 0.11 mm is plated with silver. The lead frame thus obtained is placedin a metal mold, a polyphthalamide molding material is poured in andcured, and the mold is removed.

The package-attached lead frame formed in this series of steps is suchthat, as shown in FIG. 10, the support leads 113 are embedded in theside faces of the package 102 and in the side faces of the side faceconvex components 103, which allows the package to be stably supportedup until the completion of the bending step. The light emitting element118 composed of a nitride semiconductor is bonded and fixed with anepoxy resin to the inner lead electrode 834 exposed on the inside of thewindow 101 of the package 102 formed as above.

Next, the electrodes of the fixed light emitting element and the innerlead electrodes 834 disposed inside the window of the package 102 areconnected to each other with the conductive wires 112, whose mainmaterial is gold.

The window 101 of the package 102 is filled with a sealing memberobtained by adding a diffusing agent to a silicone resin, and thesealing member is cured.

The portions that will become the outer lead electrodes 116 are then cutaway from the lead frame 117, bent along the bottom face of the packagein the direction of the back face 121, and housed in the concavecomponents 107. In this example, the distal ends of the outer leadelectrodes 116 are branched in two parts and extend in mutually opposingdirections, and one end extends toward the side face 126 of the package102.

Finally, the support leads embedded in the side faces 126 of the package102 are removed, which separates the light emitting device 100 from thelead frame. At this point, as shown in FIG. 1A, grooves 106 are formedin the side face convex components 103 and the side faces 126 of thepackage.

The light emitting device 100 formed in this manner has the grooves 106in the side faces of the side face convex components 103, and the outerlead electrodes 116 are housed in the concave components 107, whichallows the package fixed to the lead frame to be stably supported in themanufacturing process, and allows mounting defects to be reduced inmounting to a substrate or the like.

EXAMPLE 2

FIGS. 2A to 2I show an Example of the light emitting device 200 of thepresent invention.

With the light emitting device 200 of Example 2, the top face and bottomface are formed so that the thickness decreases from the front face sidetoward the back face side. A gate 234 is formed on the bottom face ofthe package so as to lead to the back face of the package. Consequently,the gate diameter can be larger, molten resin can be supplied into themold at a lower mold internal pressure, and moldability is better, so alight emitting device 200 that has less flash, is compact, and is wellsuited to mass production can be realized.

According to the light emitting device 200 of Example 2, the same effectis obtained as with the light emitting device in Example 1 above.

EXAMPLE 3

FIGS. 3A to 3I show an Example of the light emitting device 300 of thepresent invention.

As shown in FIGS. 3C and 3F, the outer lead electrodes 316 of the lightemitting device of Example 3 are housed in concave components 307 on thebottom face of the package so that they do not stick out from the sidefaces 326 of the package. The light emitting device of Example 3 hascut-outs 330 on the back face of the package, and the outer leadelectrodes 316 are disposed directly under these cut-outs 330.Consequently, the places where the outer lead electrodes 316 aredisposed can be checked from the top face direction.

Also, as shown in FIG. 3I, there are protrusions 332 on the bottom faceof the window. Providing these protrusions 332 keeps a bonding member(not shown) from leaking out to the wire bonding area when the lightemitting element 318 is bonded via this bonding member.

According to the light emitting device 300 of Example 3, the same effectis obtained as with the light emitting device in Example 1 above.

EXAMPLE 4

FIGS. 4A to 4I show an Example of the light emitting device 400 of thepresent invention.

As shown in FIG. 4F, the light emitting device of Example 4 is such thatconcave components 407 are not provided up to the front face.

According to the light emitting device 400 of Example 4, the same effectis obtained as with the light emitting device in Example 1 above.

EXAMPLE 5

FIGS. 5A to 5I show an Example of the light emitting device 500 of thepresent invention.

As shown in FIG. 5F, with the outer lead electrodes 516, the width W6and the width W7 are formed are formed to be substantially the same.

According to the light emitting device 500 of Example 5, the same effectis obtained as with the light emitting device in Example 1 above.

EXAMPLE 6

FIGS. 6A to 6I show an Example of the light emitting device 600 of thepresent invention.

As shown in FIG. 6H, with the outer lead electrodes 616, the distal endsare branched in three parts.

According to the light emitting device 600 of Example 6, the same effectis obtained as with the light emitting device in Example 1 above.

EXAMPLE 7

FIGS. 7A to 7H show an Example of the light emitting device 700 of thepresent invention.

As shown in FIG. 7A, the side face convex components 703 of the packageare rectangular in shape as seen from the front face.

According to the light emitting device 700 of Example 7, the same effectis obtained as with the light emitting device in Example 1 above.

EXAMPLE 8

FIGS. 8A to 8I show an Example of the light emitting device 800 of thepresent invention.

As shown in FIG. 8H, with the light emitting device of Example 8, theside face convex components 803 on the side faces of the package areprovided from the end of the package on the front face side to the endon the back face side, and outer lead electrodes 816 that are bent alongthe bottom face are housed in concave components 807.

With the light emitting device in this example, as shown in FIGS. 8C and8F, the outer lead electrodes 816 are formed so that they do not stickout from the package side faces when viewed from the top face and fromthe bottom face. Also, in this example, as shown in FIGS. 8D and 8E, theouter lead electrodes 816 are formed so that more than half of each oneis covered by the side face convex components 803 on the back face sideof the package (see FIG. 8H) in side face view. The result of thisconstitution is that if some force should be applied in the side facedirection, it will be less likely that problems will occur, such as theouter lead electrodes 816 being pushed and bent.

According to the light emitting device 800 of Example 8, the same effectis obtained as with the light emitting device in Example 1 above due tothe side face convex components 803.

The illustrated embodiments of the light emitting device can be utilizedas a light source that is used in liquid crystal display backlights,panel gauges, display lights, portable electronic devices, and so forth.

Description of the Numerals: 100, 200, 300, 400, 500, 600, 700,800—light emitting device; 101—window; 102, 202—package; 103, 703,803—side face convex component; 104—center convex component; 106—groove;107, 307, 407, 807—concave component; 112—conductive wire; 113—supportlead; 116, 316, 516, 616, 816—outer lead electrode; 117—lead frame; 118,318—light emitting element; 121—back face; 126, 326—side face; 230,330—Cut-out; 234—gate; 332—projection; 834—inner lead electrode; 846,848—mold; 856—support lead; 862—cavity; 866—protrusion; 864—materialpouring gate; and 868—molding material.

1. A light emitting device comprising: a package equipped on a frontface with a window for installing a light emitting element; and outerlead electrodes that protrude from a bottom face of the package, thepackage having, on the bottom face, two side face convex componentsprovided on the side face sides and a center convex component providedat a center, the outer lead electrodes being housed in a concavecomponents defined by the side face convex components and the centerconvex component, the side face convex component having groove providedon the side face.
 2. The light emitting device according to claim 1,wherein the package has at least two cut-outs, and the outer leadelectrodes are disposed directly under the two cut-outs, respectively.3. The light emitting device according to claim 1, wherein the thicknessof the side face convex components and the center convex component issubstantially the same as the thickness of the outer lead electrodes. 4.The light emitting device according to claim 1, wherein the thickness ofthe package is no more than 1.5 mm.
 5. The light emitting deviceaccording to claim 2, wherein the thickness of the side face convexcomponents and the center convex component is substantially the same asthe thickness of the outer lead electrodes.
 6. The light emitting deviceaccording to claim 2, wherein the thickness of the package is no morethan 1.5 mm.
 7. The light emitting device according to claim 3, whereinthe thickness of the package is no more than 1.5 mm.